In a large bowl, combine the olive oil, lemon juice, soy sauce, minced garlic, ground cumin, paprika, salt, and black pepper. Mix well.
Add the beef cubes to the marinade and toss to coat. Let it marinate for at least 15 minutes.
Preheat the grill to medium-high heat.
Thread the marinated beef cubes onto skewers, alternating with the bell peppers and onion wedges.
Grill the kebabs for 10-12 minutes, turning occasionally, until the beef is cooked to your desired doneness and the vegetables are tender.
Serve the grilled beef kebabs with hummus, pita bread, and mixed greens.